How to Search for Science-Based Gardening Advice


Agricola’s search page.

In the course of writing our books and this blog we’ve had to deal with a lot of thorny gardening questions such as the effectiveness of double digging, the toxicity of persimmons, compost tea, lasagna gardening and how to mulch to name just a few. While the internet is an amazing tool, the number of conflicting commercial interests, biases and crazy talk in the eGardening world can make it difficult to, as Mark Twain put it, “corral the truth.” And I have to confess to promulgating some of the questionable advice that’s out there.

In the interest of not spreading more bad information Linda Chalker-Scott, Extension Horticulturist and Associate Professor at Washington State University, did a webinar (archived online here) with a lot of great advice on how you can evaluate gardening advice as well as do your own searches of peer reviewed literature.

She suggested six databases. First the free ones:

  • Agricola–run by the USDA–not all of the contents are peer reviewed. The best thing about Agricola is that it’s free and online.
  • Google Scholar–good for a start but most of the articles you’ll find are behind pay walls and you’ll have to look them up in a university library.

The following databases are behind pay walls. You’ll need to make a trek to your local university to use them:

  • CAB is a database of 7.3 million abstracts relating to “agriculture, environment, veterinary sciences, applied economics, food science and nutrition.”
  • Biosis–A citation index for the life sciences.
  • Web of Science–information in “sciences, social sciences, arts, and humanities.”
  • GREENfile–“draws on the connections between the environment and a variety of disciplines such as agriculture, education, law, health and technology. Topics covered include global climate change, green building, pollution, sustainable agriculture, renewable energy, recycling and more.”

All of these databases overlap to some extent and you’ll probably need to check more than one to be thorough. They will also deliver results from trade and popular sources (not a bad thing, of course, but these sources are not as authoritative as peer reviewed information).

Another handy tip Chalker-Scott discussed is the use of an asterisk when searching. Say you want to find info on mulch. Some articles might use “mulches.” To broaden your search you can enter “mulch*” and you’ll get both “mulch” and “mulches.” Note that you can’t combine asterisks with exact word searches in quotation marks. You can also limit or broaden searches through the use of “and,” “or” and “not.” And when looking up chemicals you may need to enter, for example, both “hydrogen peroxide” and “H2O2.”  With plants you may need to use both the popular and scientific names.

Unfortunately, as Chalker-Scott noted, there’s a lack of practical small-scale gardening advice in peer reviewed literature. But a search of the research literature is a start and can help screen out bogus info (a lot of which comes from people trying to sell things). And knowing that there are no studies can put arguments based on conflicting anecdotes into perspective, i.e. sometimes it’s best to just say we don’t know.

My new research buddy--ProQuest showing the results for compost tea.

My new research buddy–ProQuest showing the results for compost tea.

My local librarian
Inspired by Chalker-Scott’s webinar I had a chat with a reference librarian in the science section of our central library (my favorite place in Los Angeles). While the LA public library system does not have subscriptions to the databases Chalker-Scott mentioned, it does have ProQuest, which allows you to access, with your library card, thousands of articles in magazines, newspapers and peer reviewed journals from your home. Check with your local library to see if they have a ProQuest subscription. LA Library patrons will find ProQuest under “Collections and Resources” on From there, go to “Research and Homework.” ProQuest is listed under “Research Library (ProQuest).” Click on that link, enter your library card number and you’re in business.

A brief search I did with ProQuest of phytoremediation of lead and zinc contaminated soils turned up a lot of interesting peer-reviewed articles with access to the full text. Between Agricola and ProQuest I may be able to get most of the information I need online without having to go to a university library.

The librarian also mentioned Worldcat, a kind of catalog of catalogs. With Worlcat you can enter your zip code and search public, university and private library catalogs in your area.

And I should mention the librarian. She spent a lot of time with me and said she’d be happy to help me with any research I needed to do. Hopefully our culture will not get swept away by Google and forget the importance of  librarians in helping us navigate our confusing world. Thanks to libraries,we have access to tools beyond Google.

Hot Topics
To that end, I’m thinking of making the trek to UCLA this year to look into a number of controversial horticultural and homesteading questions that have come up in the course of writing posts on Root Simple. Some topics I’m interested in:

  • The effect of chloramine on soil health/human health.
  • The temperament of Africanized bees.
  • Hugelkultur in dry climates.
  • Compost tea.
  • Phytoremediation of lead and/or zinc.
  • Rock dust in home gardens.
  • Biochar in alkaline soils.

I’m sure that some of these topics will yield no peer reviewed results but maybe I’ll find articles in trade journals.

Can you think of some topics I should look up or write about? And if you feel inspired to do some research on these issues or others let us know what you find. Hint–if you work at a university and find yourself bored, please go ahead and look some of this stuff up for me!

Leave a comment


  1. I’m a frequent reader and a less frequent commentor – I currently live overseas but will move back to Davis (not to Village Homes where regular people can’t afford a home, but still…) by summer’s end. I expect to spend lovely chunks of time in the UCDavis library and would be willing to send articles your way. I know it’s far too early for this info to be helpful to you, but I just wanted to put it out there while you’re thinking of the topic 🙂

  2. One way to solve your access-to-research questions is to marry an agronomist/horticulturist. Obviously, that’s not an option for everyone, but it has stood me in good stead. 🙂

    More to the point, my husband graduated from the University of Hawai’i’s College of Tropical Agriculture, which houses a large cooperative extension program and maintains a website with a lot of publically-available research on it ( I’m pretty sure that land grant universities all have extension programs which means that there should be reliable research on a whole host of data on crops, pests, soil science, etc., for different climates. This is the website for UC Davis’ cooperative extension service: Extension agents – people with graduate degrees who specialize in one crop, animal, or insect (e.g., bees) – are also great people to get in touch with because it’s their job to be the interface between research institutions/research and professionals in agriculture (or enthusiastic amateurs). If anything, an extension agent should be able to provide an idea of where to look for the answers to ag-related questions. They also lead workshops – at least, many do in Hawai’i.

    Good luck!

  3. Nice post! I find myself frequenting the same sources. 🙂

    I would add that for papers behind pay walls that your library can’t get, you could try e-mailing the corresponding author of the paper. They might not be able to send the actual paper, but most publishers allow the authors to keep a final draft that they can share with people.

    Professors are busy folk, so they might not respond quickly (or at all), but it’s worth a shot!

    • I could write a book about this question. I’ve looked at the research on biodynamics and it shows, basically, no difference between organic and biodynamics in terms of production. Which brings up the limits of science. Biodynamics is more of a metaphsyical pursuit. Looking at it requires the tools of philosophy and theology. While not addressing Steiner or Biodynamics, Ioan Coulianu’s difficult book Eros and Magic in the Renaissance opened my mind to an alternate view of the evolution of modern materialism. But I digress! I think some of the tools of sociology–looking at biodynamic practitioner’s belief systems–might be more interesting than just asking “do the preps work?”

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  6. Hi Mr. Homegrown,

    A research question for you (or let me know if you know where I can look for this info): Have any scientists measured the amount of ‘bad stuff’ retained within a vegetable plant that is planted in contaminated soil? I know about the effects of lead ‘splashing-up’ onto leafy vegetables from the soil, but what about tomatoes, beets, etc…? Thanks! Julie

    • Good question–I looked into it some time ago but couldn’t find anything. I will try again now that I know some better research tools. You can send plant tissue material to Wallace Labs to find out yourself but this would get expensive. I do know (thanks to Garm Wallace) that spinach is really good at pulling up bad things.

    • The reason I ask is that I’ve heard lots of talk about commercial soils that contain ‘sludge,’ or composts that have ecoli in them. This is bviously not ideal, but when it comes right down to it, what of these impurities is left inside the food we grow? That’s what I’d love to know… (rather than just repeating to each other that “its bad!”).

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